In a bidirectional installation on concrete, what action is necessary regarding the tires?

In a bidirectional installation on concrete, the correct action involves removing two tires—one from each MASS. This step is crucial as it ensures that the installation is stable and properly aligned. By removing one tire from each MASS, the machine is positioned optimally for its intended operation, ensuring that it can effectively navigate the surface while reducing the risk of any imbalance or operational hazards.

This action is particularly important in ensuring that the load is distributed evenly across the remaining tires, which helps in maintaining traction and stability. The specific focus on removing one tire from each MASS helps to ensure that the system operates efficiently while minimizing wear and tear on the equipment.

The other options refer to different actions that do not directly address the specific requirements for bidirectional installations involving stability and balance on concrete surfaces. Therefore, the decision to remove two tires from each MASS is the most effective and contextually appropriate choice.